This invention relates to an apparatus for mail sorting. In particular, the present invention relates to a computer controlled mail sorting system that eliminates the memorization of scheme knowledge and case or rack diagram knowledge inherent in previous manual mail sorting processes.
Vast quantities of mail are entrusted with postal services around the world for accurate and timely delivery. In the United States, the Postal Service processed approximately 182.7 billion pieces of mail in 1996 alone, an average of approximately 603 million pieces of mail each day. Approximately 53.3% of the mail processed was First Class mail, approximately 39.3% was Standard Mail (A) and approximately 5.5% was Periodicals. Nearly one billion pieces of mail were Foreign mail. The delivery network in the United States reaches nearly 128 million addresses and the United States Postal Service (USPS) handles over 43% of the worldwide mail volume. In comparison, Japan, the second largest carrier of cards and letters, handles only 6%. The foregoing statistics and additional information are available on the official USPS world wide web site at www.usps.gov.
The USPS in a given city, for example Chicago, generally segments the bulk mail collected between mail destined for Chicago, and mail destined for other cities ("outgoing" mail). The outgoing mail is shipped to receiving post offices located in the other cities, while the mail destined for Chicago is further sorted into Primary and Secondary mail, and finally goes through a Carrier assignment before delivery. Mail destined for sections of the city served by the main USPS office is termed Primary mail, and is delivered by routing each piece of mail to the individual carrier handling the section of the city indicated by the address. The carrier then hand delivers the mail. Mail bearing addresses handled by branch USPS offices is termed Secondary mail and is forwarded to the particular branch office handling those addresses. In Chicago, for instance, Station 41 handles secondary mail to a section of the city corresponding to the zip code 60641.At each secondary station, each piece of mail is sorted to an individual carrier handling the address on the mail. In order to efficiently handle the vast quantities of mail it is called upon to deliver, the USPS uses electronic sorting and automation equipment. From 1987-1996, the USPS committed approximately $4.3 billion for installation of equipment at postal facilities throughout the country to automate letter mail processing. The equipment includes, for example, optical readers, and delivery barcode sorters. One type of high-speed sorting apparatus is disclosed, for example, in U.S. Pat. No. 3,889,811 to Yoshimura, entitled "Flat-Article Sorting Apparatus for an Automatic Mail Handling System and the Like". Even with the sophisticated sorting equipment of today, however, a certain percentage, and consequently large numbers of pieces of mail are not read correctly (or at all) and wind up as reject letters for additional processing. Although machine handling technology has rapidly advanced, the processing of unsorted reject mail is still accomplished manually by USPS employees. In other words, high speed sorting apparatuses are unable to further sort rejected letters.
Highly trained USPS employees (hereafter "sorters") are responsible for manually sorting the reject mail. Each unsorted rejected letter must eventually be assigned to a carrier for delivery. Each carrier may, for example, be assigned to a bin in a sorting case in which the sorted mail is placed awaiting carrier pickup. In particular, when the rejected letter needs to be sorted to particular carriers for delivery, the sorters require nearly perfect knowledge of an elaborate and complicated "scheme" as well as a case diagram to perform their responsibilities.
A scheme is a mapping between addresses (or ranges of address) and bins in a case (corresponding to carriers who deliver to those addresses and to secondary stations). A scheme may require, for example, knowledge of 1000 address areas. A piece of mail that falls outside of the scheme address area is placed in a holding bin for delivery to another sorter.
Furthermore, each sorter needs to memorize a case or rack configuration. The case and rack configuration includes knowledge of where each bin in the case is located, and knowledge (in conjunction with scheme knowledge) of how each bin in the case is assigned to carriers and addresses. Even when a small number of streets and a small number of carriers exist, the number and complexity of the different possible schemes and case configurations grows exponentially.
The scheme may also include a foreign address component that directs the sorter to place letters with foreign addresses in an assigned bin. It is noted that the general term "bin" as used in this specification may correspond to holding areas in, for example, a rack (used to sort small parcels), a case (used to sort letters), or a container (used to sort large parcels). It is further noted that the mail sorting apparatus described in this specification is not limited to letters, but may be used to sort parcels, periodicals, priority mail, and the like.
Teaching sorters a scheme is a time, labor, and money consuming task. In Chicago, for instance, it is not uncommon to train a sorter for over six months before the sorter becomes proficient in a single scheme. After a sorter learns a scheme, the sorter is then limited to sorting mail destined for delivery in that scheme, and may not move to other schemes without extensive retraining. Thus, the USPS operations are sensitive to sorters who become sick and cannot work, sorters who quit, or sorters who desire to change work location.
Furthermore, many sorters in training become discouraged at the complexity of the knowledge they have to acquire, and quit partially through training. Thus a new sorter must begin training from the beginning. Assuming the sorter makes it through training, there is no guarantee that the sorter will be able to retain the complex scheme knowledge. Thus, sorters often make mistakes which lead to late delivered, reprocessed, or undelivered mail. Moreover, the complexity of the schemes, in combination with the time pressures involved in delivering the mail, contributes greatly to a stressful work environment at the USPS.
Because of the extensive training needed to teach a sorter a scheme, the USPS only reluctantly reassigns carriers to new or different routes. Such changes would require the sorter to relearn a portion of, or in some cases, all of the scheme. Thus, the USPS is hampered in its attempts to dynamically assign carriers to delivery addresses in order to keep schemes efficient as the city changes, for example, as the city grows and streets are added, extended, or changed to residential zoning.
A need has long existed in post offices for a computerized manual mail sorting system that eliminates scheme knowledge and case knowledge.